CBSE Class 9 Science Pratical: Preparation of a True Solution of Common Salt, Sugar and Alum

Experiment: Preparation of a True Solution of Common Salt, Sugar and Alum

Aim:

To prepare true solutions using:

• Common Salt
• Sugar
• Alum

in water and study their properties.

Materials Required:

• Common salt
• Sugar
• Alum
• Distilled water
• Three clean beakers
• Glass rod
• Measuring cylinder
• Spatula

Theory:

A true solution is a homogeneous mixture in which the solute completely dissolves in the solvent. The particles of a true solution:

• Are very small (less than 1 nm)
• Cannot be seen with naked eyes
• Do not settle down on standing
• Cannot be separated by filtration

Common salt, sugar, and alum are soluble substances, hence they form true solutions in water.

Procedure:

(A) Preparation of Common Salt Solution

1. Take 50 mL of distilled water in a clean beaker.
2. Add a small amount of common salt using a spatula.
3. Stir continuously with a glass rod.
4. Continue stirring until the salt completely dissolves.

(B) Preparation of Sugar Solution

1. Take another beaker and pour 50 mL of distilled water.
2. Add a spoon of sugar.
3. Stir the mixture gently.
4. Sugar dissolves completely, forming a clear solution.

(C) Preparation of Alum Solution

1. Take the third beaker and add 50 mL of distilled water.
2. Add crushed alum to the water.
3. Stir well using a glass rod.
4. A clear solution of alum is obtained.

Observations:

Substance	Appearance of Solution	Nature
Common Salt	Transparent	True solution
Sugar	Transparent	True solution
Alum	Transparent	True solution

Result:

Common salt, sugar, and alum dissolve completely in water to form true solutions which are clear, homogeneous, and stable.

Precautions:

• Use clean and dry beakers.
• Stir the solution properly.
• Do not add excess solute.
• Use distilled water for better results.

Viva Voce (Important Questions)

Q1. What is a true solution?
A homogeneous mixture in which the solute completely dissolves in the solvent.

Q2. Can true solutions be filtered?
No, they cannot be separated by filtration.

Q3. Name two examples of true solutions.
Salt in water, sugar in water.